This is the 3699th article of Da Medical Care
The largest organ of the human body is the skin, we can see and touch it every day, there is no sense of mystery, but it has a very important irreplaceable function for the human body, and it cannot be ignored.
To sum up, there are five main functions.
First, the protection function
The skin covers the surface of the body and is a natural protective barrier for the human body. The stratum corneum can prevent the loss of nutrients and water in the body, and at the same time prevent the invasion of various harmful substances; The toughness and strength of the dermis layer, the softness and elasticity of the grease layer, can effectively buffer the impact of external mechanical forces, thereby protecting the human body; Pigment cells are able to absorb ultraviolet rays, protecting the body from sunlight.
Second, sensory function
The skin contains a lot of nerve endings, so that we have different feelings such as "pain, touch, cold, heat, pressure, itching" and so on. Do not underestimate these feelings, when environmental changes or external stimuli adversely affect the body, these feelings are like the body's early warning mechanism, timely reminding us to take measures to prevent various violations.
Third, the body temperature regulation function
The fat layer is a bad conductor of warmth and plays an important role in maintaining body temperature, like wearing a thick cotton jacket for the body. The skin also emits heat through the contraction and expansion of capillaries, the reduction and increase of sweat secretion, and the physical methods of radiation, convection, conduction, evaporation, etc., thereby regulating body temperature to adapt to changes in external temperature.
Fourth, absorption, secretion and excretion functions
The skin is not a completely opaque absolute barrier, but also has the function of absorption, secretion and excretion. Some water, fat-soluble substances, and heavy metals (such as mercury, lead, arsenic, copper, etc.) salts can enter the body through pores, sweat holes, sebaceous glandular holes, and epidermal cell spaces. Through the secretion of sweat and the excretion of sebum, it can not only play a role in excreting waste products in the human body, but also form an emulsifying skin film on the surface of the skin after the two are mixed, which can moisturize the stratum corneum and prevent the skin from drying and cracking.
Fifth, immune function
The skin is the largest immune organ of the human body and has an important protective effect on the human body. The skin contains a variety of immune cells and immune factors, and is also the starting organ of the body's immune response and the place where the immune effect is performed. It plays a very important role in protecting the human body from the invasion of foreign pathogens, identifying and then marking and killing abnormal cells and senescent cells.
Author: Director of the Department of Burn Plastic Surgery, Shanghai Dianli Hospital
Zhu Weiping